Implications of ecological gradients and climate change on tree species composition, diversity and distribution in two eastern arc mountains, Tanzania
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Date
2014
Authors
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Publisher
Sokoine University of Agriculture.
Abstract
The conservation of biological diversity in the tropics is important for improving
ecosystem goods and services.
Proper conservation planning however requires a
thorough understanding of forest ecosystem processes that give rise to observed diversity
and distribution patterns. Such knowledge may reflect underlying ecological processes
that are important for management. Within forest ecosystems, plant communities have
been associated with biotic and abiotic factors that often interact to form complex
network of relationships. However, few attempts have addressed the questions of
environmental effects to tree communities in the tropics with particular emphasis on the
Eastern Arc Mountains (EAMs) of Tanzania. With recent environmental change, such
ecosystems and component species are expected to respond uniquely, raising special
conservation concerns. This study was carried out with the overall objective of
determining tree species composition, diversity and distribution patterns in the Udzungwa
(UMF) and East Usambara (EUF) Mountain forests of the EAMs as influenced by
environmental gradients and climate change. Multivariate and Maximum Entropy
Distribution Modelling (Maxent) was used in data analysis. High species richness was
observed at mid-elevations suggesting that most of the species occur at moderate climatic
conditions where growth and survival conditions are at optimal. There was a mixed
response in species composition to mean annual temperature suggesting a heterogeneous
effect of temperature on these two afromontane forests. The effects of edaphic factors
appeared to be crucial in determining plant community patterns in the EAMs. Climatic
and edaphic factors were predicted to be the main drivers of species distribution under
current and future environmental conditions. Some species were predicted to lose their
suitable habitats while others would gain through habitat (niche) expansion in response to
climate change. Gradual variations in diversity responses to temperature for the two EAM sites suggest a need to focus on local patterns of climate change rather than broad-scale
assessments. Conservation planners are advised to focus on local patterns of climate
change and avoid broad-scale generalizations in assessment of how climate change might
impact tree communities.
Description
Keywords
Biodiversity, Composition,, Climate change,, Climatic factors,, Ecological gradients,, Edaphic factors,, Eastern Arc Mountains